Semiconductor integrated circuit device

Abstract

Bit lines BL of a DRAM that are narrowed to 0.1 μm or less are made of two-layered conductive films, in which a W (tungsten) film is deposited on a WN (tungsten nitride) film. For bit lines BL, fewer W atoms diffuse across the interface between the W film and the WN film, within crystal grains, and at grain boundaries of the W film, and no tensile stress exists in the W film. Therefore, high-temperature thermal processing in the capacitor formation process does not cause wiring breaks even when the width of the bit lines BL is narrowed to 0.1 μm or less.

What is claimed is:  
     
       1. A semiconductor integrated circuit device comprising: 
       memory cells, which are located at the intersections of word lines that extend in a first direction of the major surface of a semiconductor substrate and bit lines that extend in a second direction that intersects the first direction at a right angle, and which include;  
       a memory-cell-selecting MISFET with a gate electrode that is configured in a single unit with the word line; and  
       a data-storage capacitor connected to the MISFET in series;  
       characterized in that the bit lines are formed over the memory-cell-selecting MISFET via a first insulating film and the data-storage capacitor is formed over the bit lines via a second insulating film;  
       wherein the bit lines are made of a first conductive film made of molybdenum or a molybdenum compound and a second conductive film made of tungsten that is deposited on the first conductive film.  
     
     
       2. A semiconductor integrated circuit device, as defined in  claim 1 , wherein the first conductive film is a molybdenum film, a molybdenum nitride film, a molybdenum boron film, or a molybdenum carbide film.